The present invention relates to a projector type headlamp in which reflected light from a substantially cup-shaped reflector is projected and distributed forward by a projection lens, and more particularly to a projector type vehicle headlamp which can change over light distributions by rotating a shade.
Disclosed in JP-B-06-048601 is a projector type vehicle headlamp in which a light source bulb is disposed near a primary focal point of a reflecting mirror, light emitted from the light source bulb is reflected on the reflecting mirror, the reflected light is made to converge to a secondary focal point near a meridional image plane of a convex lens and a rotational shade is disposed. The rotational shade has a rotational axis within a plane which intersects with a optical axis at a right angle and intersects with a line of intersection between a vertical plane including the optical axis and the meridional image plane of the convex lens. The rotational shade includes two light shielding plates having differently shaped cut-off lines which are mounted on an outer circumference of the rotational axis, whereby beam distribution patterns are changed by rotating the rotational axis.
In the projector type vehicle headlamp of JP-B-06-048601, beams on the basis of a plurality of light distribution patterns can be emitted. However, the light shielding plate for forming a light distribution pattern corresponding to the low beam and the light shielding plate for forming a light distribution pattern corresponding to another beam which is different from the low beam are set to a positional relation in which the light shielding plates are apart 180° from each other in the circumferential direction, and a position which is apart 90° from the respective light shielding plates is set for forming a light distribution pattern corresponding to the high beam (a light distribution pattern-suitable for driving with no oncoming vehicle). Namely, the light shielding plate corresponding to the low beam and the light shielding plate corresponding to the another beam which is different from the low beam are disposed distantly in the circumferential direction on both sides of a position for the high beam.
Therefore, when the light distributions are switched over from the low beam, which is used most frequently, to the another beam, or from the another beam to the low beam, it is inevitable that the high beam is emitted, and hence there has been caused a problem that an oncoming vehicle may be dazzled.